The invention relates to devices, including infusion apparatus, for administering an injectable product in doses. The application claims the priority of German patent application No. 100 51 371.9, filed on Oct. 17, 2000, with the German Patent and Trademark Office.
Portable injection and/or infusion apparatus are used for administering medicines in fluid form, in particular in liquid form, for example insulin. The medicinal fluid is displaced in doses from a fluid container by means of a piston, and administered. Such apparatus have a broad application in insulin treatment, as pump apparatus and manually operated injection pens. One example of an injection pen is known from WO 93/16740. The insulin pumps of Disetronic Medical Systems AG are examples of portable infusion apparatus. In general, the user constantly carries the apparatus about his/her person, for example, in the workplace or on holiday. In order to be as independent of an external supply as possible and to have freedom of movement, the apparatus should be able to hold as much medicinal fluid as possible but still be as small or compact as possible. Space-saving and convenience is generally desirable in the medical field, including for stationary apparatus and systems.
WO 98/47552 discloses a device for administering an injectable product in doses which comprises a casing, a container accommodated by the casing, from which a product dosage is delivered through an opening of the container by an advancing toward the opening a piston accommodated in the container, and a drive means. The piston is slidably moved toward the opening of the container by means of a driven member of the drive means. The drive means comprises a number of telescopic sliding stages.